The present invention relates to an electromagnetic shield cap for electromagnetically shielding an electronic component. It also relates to an infrared data communication module to which such an electromagnetic shield cap is mounted.
An electronic component such as an infrared data communication module often needs to be electromagnetically shielded for avoiding the influences of external noises. In the case where a substrate carrying an electronic component is housed in a relatively larger metal casing, an electromagnetic shield need not necessarily be separately provided for the electronic component because the casing serves as a electromagnetic shield.
Recently, however, there is an increasing demand for portable apparatus such as a mobile phone, in which a large metal casing is not employed to realize weight reduction. In such a case, conventionally, a cap formed by press-working a thin metal plate into a size substantially equal to that of the electronic component is mounted to the electronic component for electromagnetic shielding. However, the cap may come off if it is simply fitted over the electronic component. In the prior art, therefore, the cap is bonded to the electronic component with an adhesive.
However, the use of an adhesive increases the cost. Further, in mounting the cap to the electronic component, a step for applying an adhesive is additionally required. As a result, there are problems such as a reduced productivity and an increased cost in manufacturing the electronic component provided with the cap.
An object of the present invention is to provide an electromagnetic shield cap which is capable of eliminating or lessening the problems described above. Another object of the present invention is to provide an infrared data communication module provided with such a cap.
In accordance with a first aspect of the present invention, there is provided an electromagnetic shield cap to be mounted on an electronic component for electromagnetically shielding the electronic component. The electronic component includes a semiconductor chip and a seal body made of resin for sealing the semiconductor chip, wherein the electromagnetic shield cap has a projection for elastically pressing against the electronic component when the cap is mounted to the electronic component.
When the electromagnetic shield cap having the above structure is mounted to the electronic component, the projection is pressed against the electronic component. Due to such pressing action, the electromagnetic shield cap is prevented from easily coming off the electronic component. Therefore, in mounting the electromagnetic shield cap to the electronic component, a step for applying an adhesive is not necessary. As a result, it is possible to increase productivity and reduce the cost in manufacturing an electronic component provided with an electromagnetic shield cap.
Preferably, the electromagnetic shield cap may have a wall for facing the electronic component, and the projection may be formed by forming a cut on the wall and partially bending the wall in a rising manner.
According to this structure, it is possible to easily form a projection without increasing the overall size of the electromagnetic shield cap. Further, an elastic force is readily provided for the projection.
Preferably, the cap is fitted to the electronic component from a front side to a back side of the cap, and the projection may be inclined to project to a greater degree as it extends from the front side toward the back side.
With such a structure, in mounting the electromagnetic shield cap to the electronic component, the projection does not bite the cap in fitting to the electronic component. Therefore, it is possible to mount the electromagnetic shield cap smoothly.
Preferably, the projection may have a tip which is directed oppositely to the cap fitting direction.
With such a structure, when a force is exerted to detach the electromagnetic shield cap from the electronic component, great frictional resistance is generated between the tip of the projection and an outer surface of the electronic component. In the case where the electronic component has a relatively soft outer surface at a portion at which the tip of the projection engages, the tip of the projection can bite into the outer surface of the electronic component. As a result, the electromagnetic shield cap is more reliably prevented from coming off.
Preferably, the electromagnetic shield cap may have a pair of side walls spaced in facing relationship with each other for interposing the electronic component therebetween, and each of the side walls may be provided with the projection.
With such a structure, it is possible to interpose the electronic component between the paired side walls, or between the pair of projections provided on the side walls. Therefore, it is possible to suitably prevent the electromagnetic shield cap from being detached.
In accordance with a second aspect of the present invention, there is provided an infrared data communication module having a substrate, an infrared light emitting element mounted on the substrate, an infrared light receiving element mounted on the substrate, and a seal body made of resin for sealing the light emitting element and the light receiving element. The infrared data communication module is provided with a cap for electromagnetic shielding, wherein the electromagnetic shield cap is provided with a projection for pressing against at least one of the substrate and the seal body.
The infrared data communication module having such a structure has the same advantages as those described for the electromagnetic shield cap according to the first aspect of the present invention.
In accordance with a third aspect of the present invention, there is provided an electromagnetic shield cap to be mounted on an electronic component for electromagnetically shielding the electronic component. The electronic component includes a semiconductor chip and a seal body made of resin for sealing the semiconductor chip. The seal body is formed with a recess impressed by an ejector pin attached to a mold for forming the seal body. The electromagnetic shield cap has a bulging portion for fitting into the recess when the cap is mounted to the electronic component.
When the electromagnetic shield cap having such a structure is mounted to the electronic component, the bulging portion fits into the recess. Due to such fitting, the electromagnetic shield cap is prevented from being easily detached from the electronic component. Therefore, in mounting the electromagnetic shield cap to the electronic component, a step for applying an adhesive is not necessary, which leads to an increased productivity and cost reduction. Since the recess is impressed by the ejector pin used in molding the seal body, the shape of the mold for forming the seal body needs not to be specially designed.
Preferably, the electromagnetic shield cap may have a wall for facing the seal body, and the bulging portion may be formed by press-working the wall.
According to such a structure, the bulging portion can be easily provided.
Preferably, the bulging portion may be tapered with a hem extending obliquely from a flat portion around the bulging portion.
With such a structure, the bulging portion does not become a great hindrance in mounting the electromagnetic shield cap to the electronic component, so that fitting of the electromagnetic shield cap can be performed easily. Further, since the bulging portion is tapered, it is easily fitted into the recess.
Preferably, the electromagnetic shield cap may further comprise a projection for pressing against the electronic component when the cap is mounted to the electronic component.
With such a structure, the electromagnetic shield cap is more reliably prevented from coming off the electronic component.
In accordance with a fourth aspect of the present invention, there is provided an infrared data communication module including an infrared light emitting element, an infrared light receiving element, and a seal body made of resin for sealing the light emitting element and the light receiving element. The seal body is formed with a recess impressed by an ejector pin attached to a mold for forming the seal body. The infrared data communication module is provided with a cap for electromagnetic shielding, wherein the electromagnetic shield cap includes a bulging portion for fitting into the recess.
The infrared data communication module having such a structure has the same advantages as those described for the electromagnetic shield cap according to the third aspect of the present invention.
In accordance with a fifth aspect of the present invention, there is provided an electromagnetic shield cap to be mounted on an electronic component for electromagnetically shielding the electronic component. The electronic component includes a semiconductor chip, a seal body made of resin for sealing the semiconductor chip, and a convex lens provided at the seal body. The electromagnetic shield cap includes an engaging portion for engaging the lens in such a manner as to embrace the lens when the cap is mounted to the electronic component.
When the electromagnetic shield cap having such a structure is mounted to the electronic component, the engaging portion engages the lens. Due to such engagement, the electromagnetic shield cap is prevented from being easily detached from the electronic component. Thus, it is possible to positively fit the electromagnetic shield cap to the electronic component without using an adhesive.
Preferably, the engaging portion may be so configured as to engage an outer periphery of a base portion of the lens.
With such a structure, the engaging portion does not cover a large area of the outer surface of the lens.
In accordance with a sixth aspect of the present invention, there is provided an infrared data communication module having an infrared light emitting element, an infrared light receiving element, a seal body made of a resin for sealing the light emitting element and the light receiving element, and a convex lens provided at the seal body. The infrared data communication module is provided with a cap for electromagnetic shielding, wherein the electromagnetic shield cap includes an engaging portion for engaging the lens in such a manner as to embrace the lens.
The infrared data communication module having such a structure has the same advantages as those described for the electromagnetic shield cap according to the fifth aspect of the present invention.
Other features and advantages of the present invention will become clearer from the description of embodiments given below with reference to the accompanying drawings.